How to reduce surface disurbance on your HOB filter

Raise the water level.


I made something but don't have the filter anymore to show a picture of it...basically the plastic rear part of most tanks glass tops. I cut a piece made a hole for the intake tube to pass through but made sure the hole held the plastic strip tightly against the back glass and just used that to stop the "waterfall" and run off into the water.

Just attach a coarse sponge to the outflow. After a while the biofilm will cover some of it to make it blend in the environment. That's what I did until I switched to canister.